Method for recovery of diolefins



SEFMRATOR INERT GAS 1 woLK 2,386,734

METHOD FOR RECOVERY 0F DIOLEFINS Filed March 8, 1943 g shee'is-sheet 1 ATTORNEYS.

ct. 9, 19145. l. L; WOLK 2,386,734

METHOD FOR RECOVERY OF DIOLEFINS Filed March 8, 1943 2 Sheets-Sheet 2 37 cYcLoNE SEPARATOR 36 35 \y v 4o A' 23 se CC IIJ o 22 L 32 25 l 24 v-w 34 oecoMPoSER IM O 2a A'TTZoRNEY.

Patentei Oct, y9, 1**945 UNITED ,STAT

Es' PATENT f OFFICE METHOD FUR RECOVERY F D IOLEFINS' r. Louis wolk, namesvme, ons., signor to rhulips Petroleum Company, a corporation of Delame Application March 8, 1943, Serial No. 478,427

4 Claims. iCl. 26o-681.5)

The present invention relates to a method for the separation of conjugated dioleflns from mixtures containing the same by reaction with complex-forming salts. More specically, it relates to a method'for utilizing. cuprous halide reagent- This complex compound is relatively stablel under ordinary conditions of-temperature and pressure, whereas the corresponding butylene-cuprous chloride addition compounds are much less stable "under the aforesaid temperature and pressure conditions; Thus, formation of the butadiene complex affords a xn'ethod` of separating butadiene from accompanying oleiins and paramns' particularly when conditions are chosen so as to minimize oleiin complex formation and/or physireactants are contacted with nely divided reagent suspended therein for a sufficient length of time to permit complex formation on the orte hand in one stage of the process and decompomtion of complex in' another stage while the re'- agent is in a suspended state thereby. effecting cal retention' of contaminants in the reaction zone. v

It has been disclosed in co-pending applications. such as Serial No. 354,0 86 filed August 24. 1940, of Schulze, Hillyer, and Brennan,l and Serial No. 408,372 led August 26, 1941; of Schulze and Short, that dry solid cuprous chloride supported on various types of carriers may be eifecti'vely l utilized for the absorption and recovery of butadiene by complex formation. In these processes, gaseous feed mixtures containing butadiene'may be. treated byiiow through elongated beds ofthe contact material at space velocities correspondy ing, for example, to 0.2 to 0.5 liquid volume per hour of feed "per volume of reagent, where' a maior proportion of the reagent .comprises4 cuprous chloride. The complex is formed at a satisfactory rate of temperatures of about 3550 F. while decomposition of thelcomplex occurs i rapidly at temperatures of about 175 F. or

above. Such methods utilize the Areagent in the form of granular beds and the like in contrast to the essentially gaseous type of operation dis l closed herein. This type of procedure possesses definite advantages due to eiilcient contact, conservation of heat and shorter contact times per.'

mitting greater volume 'productionuwithgiven invention the' quantities of reagent. l

In accordance with the present reaction anddecomposition under optimum conditions of contact and heat exchange. In one form of the invention described below. nely divided reagent particles which may be a cuprous halide such as. chloride or bromide, or other complex-forming inorganic metal .salt of a heavy metal of groupI or 1I of the periodic system,

are carried through absorption, heat exchange,

and decomposition zones in suspension in a stream of gaseous diolen-containing feed at.

temperatures at which complex formation will take place Preferably the reagent particles may range from about 20 to about 200 microns in size and particles of about 100-400 mesh are suitable.l 'I'he feed ispassed through the zones at a velocity sufficient to maintain the particles in suspension v and at a rate which will give the desired contact time. In vertical chambers' .a gas velocity of 1-10 feet per second may be suitable, the lower.

velocities being utilized for the 'more nely divided reagent (and the higher velocities for heavier particles. The use of more finely divided particles will permit .shorter contact times and v shorter absorption zones, while larger particles and greater gas velocities will require somewhat longer contact time and more elongated absorption zones or recycle vof suspension Similar velocities may be provided in the desorption and heat exchange zones hereinafter described.

In order to ensure substantially complete ab.

sorption of dlolen a ratio of reagent to dioleiln is preferably provided in the suspension in which the reagent is present in excess of the stoichiometric amount required for the reaction. For example, two 'mois of cuprous chloride are required to combine with each mol of butadiene. in other words the gasshould contain in susmuch cuprous -chloride as butadiene by weight.

Preferably the excess of cuprous chloride should not -be too great since this would require handling of .excessive quantities ofreagent.. Ordinarily from one to two times'the stoichiometric equivalent of cuprous halide is -sufllcient. A contact time ranging from. l0 to 100 seconds is generally adequate to provide substantial absorption o f dia I olefin under the conditions described above.

operating the present method. reference pension .approximately at least four times asreaction:

vcold complex in cupi-ous chloride is reintroduced into absorption may be had to a'form of apparatus described in Figure l.

Cuprous chloride of 100-400 mesh in line I0 is admixed with gaseous feed in line I containing 10 per cent or more butadiene in admixture with other C4 hydrocarbons; the stream of hydrocarbon and reagent suspended therein ows through absorbing zone 2 at a ow rate suicient to permit substantially complete reaction between the butadiene and CuCl in accordance with the following This reaction preferably is carried out at temperatures' between about 35-50 F. The gas stream containing complex, and C4 hydrocarbons other than butadiene with some unreacted material. is introduced into cyclone separator 3, the butadiene-free gas escaping while the solid complex is deposited and flows by gravity or byconveyor means through linel 4 to zone 5 where it is' met by a stream of hot butadiene and inert gas from decomposition zone 8 as hereinafter described, T'ne complex becomes suspended in this gas stream and is raised to a more elevated temperature, that is, the gas stream may be at about 175 F. While the complex may be at 50 F. The resulting temperature of the complex may be about 100 F. when it leaves zone 5 while the temperature of the gas stream will also be about 100 F. The suspension is introduced into cyclone separator F3 and the solid complex deposited out, the gas stream containing inert gas and butadiene passing to separator ifi where butadiene is recovered by condensation or solvent extraction, the cool inert gas being utilized as hereinafter described. Any particles which may deposit in zones E, Si, or il may be removed from the bottom of said zones by means not shown.

The preheated complex hows through line i by gravity or mechanical means into decomposing zone 8 at the entrance to which it meets the stream of inert gas from separator it, which has previously been preheated either by heat exchange with gaseous etiluent from cyclone separator 0, or by contact with hot cuprous chloride separated in by direct heat exchange therewith or by some other heat exchange means. The complex. is heated in zone to decomposition temperatures of from 175 to 250 F. by heating coils in said zone or by rst preheating the inert gas to the desired temperature. Cuprous chloride is recovered incyclone separator s while the mixture of butadiene and inert gas is used topi-cheat as described above. The

or reaction zone 2 after cooling to absorption temperature in heat exchanger I2 Where the cold inert gas from separator Irl may be used as a direct or indirect heat exchange medium. If it is desired to separate the butadiene :from the inert gas stream leaving separator 9 as soon as possible, this stream may be cooled to separate butadiene. after which the inert gas may be preheated by contact with hot deserted cuprous 'e chloride from 9 in indirect or direct heat ex-` change as by suspending the cuprous chloride ditions in which polymerization might occur and represents an alternate procedure.

As inert gas, low-boiling relatively incondensible hydrocarbons such as methane, ethane. or propane may be used, or inert gases such as 'nitrogen or CO2. Mixtures of the foregoing may 10D-200 mesh is introduced at the top of the abtherein followed by separation, this preheated Y inert gas may then be used for preheating the cold comples in 0 in place o! the butadiene-inert sas mixture. In this modification cyclone sepa@ rator E may be by-passed, the suspension going directly into desorber a where desorption temperatures are provided. This will obviate the necessity for handling the butadiene under conbottom of the reaction zone.

and the particle size of the cuprous chloride'are' correlated so that a desired contact time is establishedand at least the major portion of the complex formed drops into hopper 24. Working with reagent of uniform particle size, the velocity of :dow may be such that the reagent particle remains suspended in the gas stream until its mass has increased due to reaction with butadiene to a point which will enable it to drop to the bottom. Velocities somewhat lower than those described in connection with the modiiication or Figure i may be utilized in order to permit differential separation of complex at the With a reagent size of about 203 mesh, a gas velocity of 1-2 feet per second will permit settling of a substantiai proportion of the complex. This will enable substantially continuous separation of completely reacted reagent at the bottom of the absorber where it is withdrawn through line 25 and conveyor 20 into heater 2l' through which hot furnace gases or steam are introduced by line 28 and. removed by line 29 in indirect heat exchange at a rate suilclent to increase the temperature of the complex to about 200 F. at which vtemperature decomposition takes place. Butadlene liberated is removed through line 0D. The regenerated cuprous chloride is continuously removed by conveyor `fil and introduced into cooling tower 32. One mode of cooling the hot reagent to absorption temperatures ci below about 50 F. is to introduce relatively cold inert gas such as methane through 3i at a velocity sumcient to elevate the reagent particles through the cooling tower which may also be refrigerated. At the point of entry to the cooler, the reagent is at about F. 'and contact with cold gas and passage through the cooling tower will permit cooling to below about 50 F. Fresh reagent may be introduced at 3l. The cooled reagent suspended in inert gas is passed through line 35 into cyclone separator 30 and ows into the absorber through line 23 while the separated gas leaves through I1. The inert gas thus serves to transport and cool the reagent While at the same time ushing it to remove minor amounts of adsorbed hydrocarbons. 'I'he butadiene-free ses, together with any suspended 'reagent and/or complex which may be carried along is passed into cyclone separator 38, the solid material being deposited and introduced into heater 21 through line Sie. The residual hydrocarbon is removed from the system through line 4t. The

to variations in particle size of reagent, separation will be effected both at top and bottom.

Iclaim:

1. A process for the separation of butadiene from gas mixtures containing the same which comprises suspending nely divided cuprous chloride in said gas-mixture at a temperature and for a period of time suilicient to permit for-- sition thereof, separating the gas stream conf taining liberated butadiene and inert gas while in a heated condition from the regenerated cuprous chloride particles, contacting said gas stream with relatively cold complex particles to preheat same and lower the temperature of the gas stream, and separating the butadiene from the inert gas.

2. A process for the recovery of butadiene from a gas stream containing the same which comprises suspending nely divided cuprous chloride particles in said gas stream, ilowing said stream through an absorption zone maintained at a temperature of about 35-50 F. for a period oi time suicient to permit formation of cuprous chloride-butadiene complex, separating said complex from said gas stream, suspending the separated complex in a stream of inert relatively incondensible gas heated to a temperature between about 175 and 250 F. in a desorption zone whereby butadiene is liberated from said complex, separating cuprous chloride particles from suspension in said inert gas stream containing liberated butadiene, separating butadiene irom said gas stream, and returning separated cuprous chloride and inert gas to the process.

3. A process for the recovery of butadiene from a gasv stream containing the same which comprises suspendingnely divided cuprous chlo-A ride particles in said gas stream, owing said stream through an absorption zone maintained at la. temperature of about 35-50 F. for a period of time sufilclent to permit formation of cuprous chloride-butadiene complex, separating said complex from said gas stream, suspending the separated complex in a stream of inert lrelatively incondensible gas heated to a temperature of about 17E-250 F. in a desorption zone whereby butadiene is liberated from said complex, separating cuprous chloride particles from suspension in said inert gas stream containing liberated butadiene, contacting said inert gas stream containing liberated butadiene with relatively cold complex separated from said absorption zone and thereby preheating said cold complex and cooling said inert gas stream containing liberated butadiene, separating said cooled inert gas containing butadiene from the preheated complex, separating butadiene fromaid cooled inert gas stream containing the same, and returning se ted cuprous chloride and inert gas to the process.

4. A process for the .separation of conjugated diolens from gas mixtures containing the same which comprises suspending nely divided cuprous halide particles inisaid gas mixture at a temperature and for a period of time sumcient to permit formation of a dioleiln-cuprous halide complex, separating the solid complex particles thus formed from the residual gas, decomposing said particles oi complex by suspending same in a stream oi' hot inert gas at a temperature and for a period of time sumcient to eiect decomposition thereof and liberation of the dioleiln, separating the 'gas stream containing liberated dioleiln and inert gas from the'regenerated cuprous halide particles, and separating the dioleiin from the inert gas.

I. LOUIS WOLK. 

